Most of the horses I ride at work are wonderfully smooth on the trot, so much so that I'm able to comfortably sit with my nice long stirrups and never feel like I'm about to bounce off.
There are a couple, though, that are pure pogo-stick on the trot, and here's where my problem comes in: If I shorten my stirrups on the bouncy trotters, I get massive ankle pain from my legs being at weird angles throughout the ride. Leaving the stirrups at a comfy length, on the other hand, means that I don't have (enough) room to stand in them for a jockey-trot or a posting trot.
The other snag in this situation is that my preferred horses usually get assigned to customers since they're easy enough for greenhorns to ride, and since we're booked solid these days, there aren't any spares for me to claim ahead of time.
So I'm wondering what I need to do in the situations where I'm required to ride a bouncy horse. Are there other factors that come into play that I might be overlooking?